Sam Warburton ruled out of third Test for the British and Irish Lions

British and Irish Lions captain Sam Warburton has been ruled out of Saturday's Test series decider against Australia in Sydney.

The Wales flanker suffered what the Lions have described as "a significant tear" in his left hamstring during the second Test defeat in Melbourne two days ago.

Warburton will remain with the squad, and it now looks as though Brian O'Driscoll will take over as skipper.

Warburton said: "It is incredibly disappointing to be ruled out of the tour through injury as we head to Sydney for the deciding match.

"I wish the team all the best and hope I can play some part in the build-up this week.

"I am confident that the boys can finish the job off and secure the series win."

The loss of Warburton is a major blow to the Lions, especially given his outstanding performance at the critical breakdown area in Melbourne.

And it means the Lions will be without both Warburton and Ireland second row talisman Paul O'Connell, who broke his arm in the first Test, as they target a first series victory since beating South Africa 16 years ago.

Lions head coach Warren Gatland is due to announce his starting line-up for Sydney on Wednesday, and it would be a major surprise if 34-year-old O'Driscoll did not take the reins for what would be his ninth Lions Test spanning four tours.

In terms of the back row rejigging that will now be required, Ireland's Sean O'Brien would appear to be in pole position for the number seven shirt vacated by Warburton, packing down between Dan Lydiate and Jamie Heaslip.

Warburton remained in Melbourne yesterday to undergo a scan while the rest of the Lions squad headed for a couple of days' rest and recuperation on Queensland's Sunshine Coast.

The Lions said in a statement that Warburton remained under the supervision of team doctor Eanna Falvey "to undergo a whole medical assessment".

Warburton, despite being only 24, has enjoyed a glittering career, leading Wales to the World Cup semi-finals in 2011 and being part of successive Six Nations title-winning teams.